PLASMA ETCHING METHOD

Abstract

A plasma etching method includes the step of etching a lower organic material film by using an upper organic material film and an intermediate layer as a mask in a processing chamber of a plasma etching apparatus, while using an etching gas made up of a gaseous mixture including an O2 gas and a carbon-containing compound gas which has a carbon atom in a molecule, to thereby transfer a pattern of the intermediate layer to the lower organic material film. A ratio of a flow rate of the carbon-containing compound gas to a total flow rate of the etching gas ranges from about 40 to 99%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross sectional view showing a schematic configuration of a plasma etching apparatus adequate for performing a plasma etching method in accordance with an embodiment of the present invention;

FIG. 2 shows a configuration example of a processing gas supply system;

FIG. 3 illustrates another configuration example of the processing gas supply system;

FIG. 4 presents a schematic view showing a surface structure of a semiconductor wafer, especially showing a patterned upper resist film;

FIG. 5 depicts a schematic view showing a surface structure of the semiconductor wafer, especially showing a state after etching a SOG film;

FIG. 6 sets forth a schematic view showing a surface structure of the semiconductor wafer, especially showing a state after dry development;

FIG. 7 provides a schematic view showing a surface structure of the semiconductor wafer, especially showing a state after forming a recess by etching; and

FIG. 8 is a graph showing a relationship between a flow rate ratio of CH₄/O₂ and a bottom CD.

Claims

1. A plasma etching method for performing an etching on a target object having a lower organic material film, an intermediate layer formed of an inorganic material and an upper organic material film, which are formed on a base layer in that order, the intermediate layer and the upper organic material film being patterned, the method comprising the step of: etching the lower organic material film by using the upper organic material film and the intermediate layer as a mask in a processing chamber of a plasma etching apparatus, while using an etching gas made up of a gaseous mixture including an O2 gas and a carbon-containing compound gas which has a carbon atom in a molecule, to thereby transfer a pattern of the intermediate layer to the lower organic material film, wherein a ratio of a flow rate of the carbon-containing compound gas to a total flow rate of the etching gas ranges from about 40 to 99%.

2. The plasma etching method of claim 1, wherein the carbon-containing compound gas is a Co gas.

3. The plasma etching method of claim 2, wherein a ratio of a flow rate of the CO gas to the total flow rate of the etching gas ranges from about 50 to 99%.

4. The plasma etching method of claim 1, wherein the carbon-containing compound gas is a CH4 gas.

5. The plasma etching method of claim 4, wherein a ratio of a flow rate of the CH4 gas to the total flow rate of the etching gas ranges from about 40 to 60%.

6. The plasma etching method of claim 1, wherein the plasma etching apparatus is a capacitively coupled plasma etching apparatus which generates a plasma by producing a high frequency electric field between a pair of an upper and a lower electrode facing each other.

7. The plasma etching method of claim 6, wherein a high frequency power ranging from about 500 to 1000 W for plasma generation is applied to the upper electrode, while a high frequency power raging from about 100 to 300 W for ion attraction is applied to the lower electrode.

8. The plasma etching method of claim 6, wherein a high frequency power ranging from about 500 to 100 W for plasma generation and a high frequency power ranging from about 100 to 300 W for ion attraction are applied to the lower electrode.

9. The plasma etching method of claim 6, wherein a high frequency power for plasma generation is applied to the upper or the lower electrode at a power density ranging from about 0.94 to 1.88 W/cm2.

10. A computer executable control program, which controls, when executed, a plasma processing apparatus to perform the plasma etching method of claim 1.

11. A computer-readable storage medium for storing therein a computer executable control program, wherein the control program controls, when executed, a plasma processing apparatus to perform the plasma etching method of claim 1.

12. A plasma processing apparatus comprising: a processing chamber for performing a plasma etching on a target object;a support for mounting the target object thereon in the processing chamber;a gas exhaust unit for depressurizing the processing chamber;a gas supply unit for supplying a processing gas into the processing chamber; anda control unit for controlling the plasma etching method of claim 1 to be carried out in the processing chamber.